Fixed Point Algorithm for COHb Calculation in Carbon Monoxide Detectors
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current carbon monoxide detectors require complex calculations to estimate carboxyhemoglobin (COHb) levels, necessitating powerful processors and increased code size, which raises costs and reduces battery life, while failing to meet UL 2034 standards for alarm response times.
Innovation Solution
A carbon monoxide detector using a fixed point algorithm to approximate the Coburn, Forster & Kane Equation, simplifying COHb calculations by employing a scale factor and integer coefficients, allowing for reduced processor requirements and smaller code size, while maintaining compliance with UL 2034 standards.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the Coburn, Forster & Kane Equation is used to calculate COHb levels, then measurement precision is improved, but device complexity increases and battery life decreases
Solution Approach 1:
The patent transforms the complex Coburn, Forster & Kane Equation into a simplified parameter-based calculation using pre-determined constants (A=0.9948, B=353, C=894, D=21.8) and a scale factor (2^20). This parameter transformation maintains measurement precision while dramatically reducing computational complexity, allowing implementation on simple 8-bit microcontrollers without requiring sophisticated processors.
Solution Approach 2:
The patent replaces expensive, complex processing hardware with a simple, fixed-point mathematical algorithm that can be executed on inexpensive 8-bit microcontrollers. This substitution of computational approach for computational power reduces device complexity and cost while maintaining the required measurement precision for COHb calculation.
2Measurement precision
If the Coburn, Forster & Kane Equation is used to calculate COHb levels, then measurement precision is improved, but loss of energy increases
Solution Approach 1:
By converting the complex continuous mathematical equation into a discrete fixed-point calculation with pre-computed parameters, the patent dramatically reduces the computational operations required. This parameter transformation reduces processor workload and power consumption while maintaining the accuracy needed for safe COHb level detection.
Solution Approach 2:
The patent replaces the mechanical/computational burden of complex real-time mathematical operations with a simplified algorithmic approach using fixed-point arithmetic and pre-calculated constants. This substitution reduces the energy required for each calculation cycle, extending battery life while preserving measurement precision.
3Measurement precision
If the Coburn, Forster & Kane Equation is used to calculate COHb levels, then measurement precision is improved, but manufacturing precision worsens due to increased cost
Solution Approach 1:
The patent transforms the complex equation into a form using simple integer arithmetic with pre-determined parameters (A, B, C, D constants and scale factor). This parameter simplification enables implementation on inexpensive 8-bit microcontrollers, dramatically reducing bill of materials cost while maintaining the measurement precision required for medical-grade COHb calculation.
Solution Approach 2:
The patent substitutes expensive high-performance processors with inexpensive 8-bit microcontrollers by using a simplified fixed-point algorithm. This substitution of computational hardware with computational efficiency reduces manufacturing cost while preserving the measurement precision needed for accurate COHb level determination.
4Measurement precision
If the Coburn, Forster & Kane Equation is used to calculate COHb levels, then measurement precision is improved, but device complexity increases due to larger code size
Solution Approach 1:
The patent converts the complex mathematical equation into a fixed-point calculation using pre-computed parameters (A=0.9948, B=353, C=894, D=21.8, scale factor=2^20). This parameter transformation reduces the algorithm to simple integer arithmetic operations that require minimal code, fitting easily into the memory constraints of 8-bit microcontrollers while maintaining measurement precision.
Data Source
AI summary
A gas detector and method of operating the gas detector that includes a carbon monoxide sensor and a processor. The carbon monoxide sensor senses an environmental concentration of carbon monoxide and provides the sensed value to the processor. Upon receiving the value of the carbon monoxide level (COppm), the processor determines an alarm threshold level based upon the COppm level. Once the alarm threshold level is determined, the processor calculates the COHb percentage for the current COppm reading based upon a derived, fixed point equation. The processor activates an audible/visual indicator when the sensed COHb percentage exceeds the alarm threshold.